Tanning agents and methods of treating hides and skins therewith



Patented Oct. 1, 1 946 Y AGENT AND "Marnons or m a e-E WSW-813111;?!-

' William; o. Ellenbogen, York, Pa.

, 1 The present invention rel-ates to the tannin f hids and skins} and particularly to tarin ing processes" employ} as the tanning agent compounds or 'xtures of c-oinpouridscontainmatron; t-. r ,7 =1 ,-1='.: ;-'.1:'.: x Va ouscompounds or substances containing nom nate teen usd -foitanning purposes iii-the past," blitin 'practieany an ass t lie" leather obtained was not ery r'esistan't to tearing nor stable on storing. Thus iron tanneddeather-tended to aey haragana iagenerar pr'oved tobe --unsatischrome-tanned leather. f 4

It isaccordingly aprimary objectof this in-'- vention to provide a iiiethod of tanning with iron cciripounds'"which results in leatHer 'of good tentile sitr'en'gth and-increased resistance to aging. Afurth'er' object of the'invention is to provide improved '--iron=contaihirig tanning agents which are'ea'pable 6f preeucmg leathers haying-not 'only the above desirableproperties but' -increasedf fullnes's anaseefr resistance.-"

*' Still furtherobjectsand advantagesoi the inventicd will appear fforrithfalldwiflg 'tfe Scfi-pti'onand appended claims- I "The-inventiona "be carried cutby treating hides or skins with dilute aduebus solutiofisf conn'g'ya ferric 'salt; steamer a short chain mono 'ycai'bbxyl-ic acid hayingat leastf one 7 hytotemof i a polycarboxylie acid haying atf least T amidine of a hi'giiei oblong-chain fatty acid. Prior to b'jecting-the hides or'skins tci -the acor he above solutions {of the purpos of tanning the samefthe -hides may be conditioned in th usual way. as tor exampl by d air n batifigafid pickling the-same; It is also customary subsequently to fix the tan with a dilute solution of alkali bicarbonate or other equivalent alkali, after which the leather is tumbled and washed, and subjected to the usual treatment following tanning, such as fat liquoring, dyeing,

drying and finishing. It is to be understood, however, that the invention is not to be limited to these customary procedures as applied either before or after the tanning.

In carrying out the tanning step as hereinbefore described any suitable ferric salt may be used, such as ferric sulfate, ferric chlorideand ferric fluoride, or *mixtures'thereof. The mono or polycarboxylic acids which may be used in the form of their alkali salts include tartaric, citric, glycolic, malic, phthalic and maleic acids. As suitable amidines there may be used oleyl amidine, stearyl amidine, the amidine of palm when cam-pared 'ye 'getable-fior 7 Claims. 1 (er s-194. 2g;

nut'oii fatty .acid',1as well as derivatives of such amidinfesi in which one or more of thehydrogen atoms attached to "nitrogen is replaced with a s rai t" f ib i ed f chain, al p t rad cal. The amidines areu'sually"employed'in the i orm o'ione of 'their'additionlsaltstsuch as the chloride or sulfate, butinscme'instances it is possibleto use the amidine per se,-" :as when sufiicient acid is furnished to ,the tanning solution from other sfou'n es o s res lt o ft e tr a ment el m The ionowingexam ies wmilzurth r illustrate the nature of invention and how it may be carrieaootin practicaput it islto be understood that th invntionis 1 9l1inffitedto thedetails dr scjribed' therein, .exceptias defined in the appended Grams. :1 I:

bath insmalkadditions zatiintervalsv over: azpe'riod of one hour. =1 i'lhis fixed. thetan. =The I leather I wasthen :tumbled. foraanother half hour, after which it was washed in water; 'rltzwas themsubfiec'ted; .t'o the susual'. steps-ifollowing itanninggineluding fat liquoring, dyeing, drying and finishing.

Example II One hundred pounds of cow hide (lime split weight), which had been dehaired, limed and bated in the usual manner, were pickled for two hours in a solution consisting of 6 gallons of water, 2 pounds of 66 B. sulfuric acid and 9 pounds of common salt. A tanning solution consisting of 8 pounds of ferric sulfate, 4 pounds of sodium tartrate, 1 pound of the hydrogen chloride addition salt of oleyl amidine and 1 pound of caustic. soda dissolved in sufiicient water to make 5 gallons, was then added. The hides were tumbled in the resulting solution for about 2 hours. Six pounds of sodium bicarbonate were then added to the bath in small additions at intervals over a period of one hour, which fixed the tan. The resulting leather was then fat liquored, dried and finished in the usual manner.

Example III One hundred pounds of calf skin (pickled Weight), which has been dehaired, limed, bated and pickled in'the usual-manner, were tanned by tumbling them for two hours in a tanning solution consisting of 8 pounds of ferric sulfate, 4 pounds of sodium glycolate and 1 pound of the hydrogen chloride addition salt of stearyl ami-, dine dissolved in sufiicient water, to make 5 gal lens. The resulting leather was then further treated and finished as described in Example I.

Example IV One hundred pounds of steer bellies (pickled weight) which had been treated in the usual Example V .Four hundred pounds of cow hide (limed weight), which had been dehaired, limed and hated in the usual manner, were pickled in a solution consisting of 35 gallons of water, 4 pounds of 66 Be. sulfuric acid and 32 pounds of common salt for about twenty minutes. The pickledhides were then tanned by tumbling them for two hours in a tanning solution prepared by dissolving 32 pounds of ferric sulfate, pounds of cream of tartar, 6 pounds of caustic soda and 3.'pounds of the hydrogen chloride addition salt of oleyl amidine'in sufficient. waterv to make gallons. Twenty pounds of sodium bicarbonate were then added to the bath' in small additions at intervals over a period of one hour, which fixed .aboveexamples were found to'have a fine and smooth grain, and a full round feel. Moreover,

they possess exceptionally high tensile strength and resistance to scuffing, and have very good aging characteristics substantiallyequal to, or

even better in someinstances than those of chrome-tanned leather.

The tanning. solutions employed as described 4 herein may be prepared either by separately adding and dissolving the various ingredients constituting the active tanning agent, or by previously mixing these ingredients and then dissolving the mixture.

It is believed that the various constituents of thetanning solutions described herein interact, when dissolved, to formorganic iron' complexes which raise the precipitation point of the iron, thereby allowing proper penetration of the tanning agent into the hide. Regardless, however, of the way the materials interact in solution, they produce the above described desirable efiects on the leathers tanned therewith.

Where mention is made herein and in the appended claims of oleyl amidine and stearyl amidine, it is to be understood that this has reference to the amidines of oleic and stearic acids respectively.

What I claim is:

l. A tanning agent comprising an. iron salt, a substance selected from the group consisting of the salts ofhydroxy mono and polycarboxylic acids and polycarboxylic acids having at least one double linkage, and a substance selected from the group consisting of the salts of amidines of higher fatty acids and derivatives of such amidines in which at least one of the hydrogen atoms attached to nitrogen is replaced by an aliphatic radical.

2. A tanning agent comprising ferric sulfate, sodium tartrate and a salt of oleyl amidine.

3. A tanning agent comprising ferric sulfate,

I sodium citrate and a salt of oleyl amidine.

4. A tanning agent comprising ferric sulfate, sodium tartrate and a salt of stearyl amidine.

5. The process of tanning hides or skins which comprises treating them with an aqueous solution containing an iron salt, a substance selected from the group consisting of the salts of hydroxy mono and polycarboxylic acids and polycarboxylic acids having at least one double linkage, and a substance selected from the group consisting of the salts of amidines of higher fatty acids and derivatives of such amidines in which at least one of the hydrogen atoms attached to nitrogen isreplaced by an aliphatic radical.

6. The process of tanning hides or skins which comprises treating them with anaqueous solution containinga ferric salt, an alkali tartrate and a salt of an amidine of a higher fatty acid. 7. The process of tanning hides or skins which comprises treating them with an aqueous solution containing a ferric salt, an alkali citrate and a, salt of an amidine of a higher fatty acid.

WILLIAM C. ELLENBOGEN. 

